Trunked radio communication systems are known to include a communication resource controller, sometimes referred to as a central controller or zone controller, for allocating RF communication resources among communication devices, including mobile or portable wireless communication units and base site RF transceivers (sometimes called “base site repeaters”) that are distributed among one or more sites. The communication resource controller may reside within a single device or multiple devices and may be located at a fixed equipment site or may be distributed among various base sites. The RF resources may comprise, for example, narrow band frequency modulated channels, time division modulated slots, carrier frequencies, frequency pairs, or generally any medium for communicating information, such as voice, video, or data traffic (“payload information”) or control signaling (“control information”) to and from the communication units and/or RF transceivers over wireless link(s).
Historically, a wireless communication unit desiring to participate in a communication sends a call request to the communication resource controller for access to a communication resource. Often, the call request is sent via a control channel dedicated for control traffic. The request usually includes an identification (ID) of the communication unit, an identification of a target communication unit, or units and may designate a particular type of service. For example, the request may be for a talk group call which can be made up of communication units and/or consoles at different sites desiring to participate in a group or dispatch call. Upon receiving the request, the communication resource controller grants the request based on authorization of the communication unit for the requested service and an availability of communication resource(s) to support the request. Upon granting the request, the communication resource controller allocates communication resource(s) to support the communication and transmits a communication resource allocation message (e.g., call grant message) to at least the initiating and target devices, typically on the control channel. Thereafter, participating communication units may access the allocated communication resource to partake in the communication.
Oftentimes, trunking systems partition the available communication resources for use by different user groups which may correspond, for example, to different organizations, grades of service, priorities and/or radio capabilities. For example, consider a site having five narrowband channels: channel 1 may comprise a dedicated control channel, channels 2 and 3 dedicated for user group A (e.g., police), channel 4 dedicated for user group B (e.g., fire) and channel 5 dedicated for user group C (e.g., animal control). Alternatively, channel(s) may be partitioned for use by multiple groups. For example, channels 2, 3, 4 and 5 could be partitioned for use by either user group A, B or C and assigned dynamically by the communication resource controller. In either case, the determination of communication resource availability heretofore has been made by the communication resource controller based on mapping the ID of the requesting communication unit to a particular user group, then determining the availability of communication resource(s) associated with that group. To that end, the communication resource controller maintains a database that keeps track of the unit ID of each individual communication unit in the system and its currently associated user group.
This method of communication resource allocation works very well in many trunking communication system applications but is subject to inefficiencies in some instances. For example, most particularly where a communication unit desires to communicate relatively short bursts of information (e.g., packet data), the practice of requesting channel access from the communication resource controller via the control channel before obtaining access to a communication resource can result in a disproportionate amount of control traffic for service requests and grants. Moreover, maintaining a mapping, by the communication resource controller, of communication unit ID to user groups can be inefficient, particularly where the communication resource controller is distributed among multiple sites and/or where there are multiple communication units in the system.
Accordingly, it would be desirable to allow for wireless communication units to send and/or receive messages autonomously in some instances (i.e., without requesting resources from the communication resource controller) and hence, without using the control channel. At the same time, it would be desirable to provide for requested access as may be appropriate in other instances and for controlling the provisioning between autonomous and requested access for loading purposes. Further, it would be desirable for a communication resource controller to allocate communication resources partitioned for autonomous or requested access by different user groups at a site without relying on a mapping of communication unit ID's to user groups. The present invention is directed to satisfying these needs.